Crystal structure and Hirshfeld analysis of 2-(5-bromo­thio­phen-2-yl)aceto­nitrile

Pappenfus, T.M.; Wood, T.L.; Morey, J.L.; Wilcox, W.D.; Janzen, D.E.

doi:10.1107/S2056989018000968

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ISSN: 2056-9890

Volume 74| Part 2| February 2018| Pages 189-192

https://doi.org/10.1107/S2056989018000968

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Crystal structure and Hirshfeld analysis of 2-(5-bromothiophen-2-yl)acetonitrile

Ted M. Pappenfus,^a Tiana L. Wood,^a Joseph L. Morey,^a Wyatt D. Wilcox ^a and Daron E. Janzen ^b ^*

^aDivision of Science and Mathematics, University of Minnesota, Morris, MN 56267, USA, and ^bDept. of Chemistry and Biochemistry, St. Catherine University, 20204 Randolph Avenue, St. Paul, MN 55105, USA
^*Correspondence e-mail: dejanzen@stkate.edu

Edited by D. Chopra, Indian Institute of Science Education and Research Bhopal, India (Received 10 January 2018; accepted 15 January 2018; online 19 January 2018)

The title compound, C₆H₄BrNS, crystallizes in the space group P2₁/n with one complete molecule in the asymmetric unit. The non-H atoms are nearly planar (r.m.s for non-H atoms = 0.071 Å), with the nitrile group oriented antiperiplanar with respect to the thiophene S atom. Intermolecular Type I centrosymmetric Br⋯Br halogen interactions are present at a distance of 3.582 (1) Å and with a C—Br⋯Br angle of 140.7 (1)°. Additional weaker C—H⋯N, C—H⋯S, and S⋯π interactions are also present. A Hirshfeld analysis indicates Br⋯Br interactions comprise only 1.9% of all the interatomic contacts.

Keywords: crystal structure; thiophene; nitrile; Hirshfeld analysis; halogen interactions.

CCDC reference: 1817195

1. Chemical context

Cyano-substituted molecules have found widespread use as functional materials for a variety of applications in organic electronics (Kim & Lim, 2014 ). For example, the title compound, 2-(5-bromothiophen-2-yl)acetonitrile, has been incorporated into materials for use in organic semiconductors (Park et al., 2016 ), sensors (Ding et al., 2015 ), dye-sensitized solar cells (Li et al., 2016 ), and organic solar cells (Kwon et al., 2015 ). Although the chemical literature has previously identified the title compound, 1, as a liquid (Cho et al., 2004 ; Chung et al., 2009 ; Lu et al., 2014 ; Wan et al., 2009 ; Zou et al., 2009 ), we have found that with proper purification, this molecule crystallizes under ambient conditions.

2. Structural commentary

The molecular structure of 1 is illustrated in Fig. 1. The asymmetric unit is composed of one complete molecule of 1. The C1—C2, C2—C3, and C3—C4 bond lengths are consistent with some conjugation in the thienyl π-system (Table 1). While both the C4—C5 and C5—C6 bond lengths are consistent with single C—C bonds, the C5—C6 bond length is shorter, likely as a result of the sp hybridization at C6. Although conjugation across the molecule is not evident from the pattern of bond lengths, the structure is remarkably planar with an r.m.s. deviation from planarity of 0.071 Å for all non-hydrogen atoms.

Table 1
Selected bond lengths (Å)

C1—C2	1.343 (6)	C4—C5	1.523 (7)
C2—C3	1.436 (6)	C5—C6	1.468 (7)
C3—C4	1.344 (7)

Figure 1
A displacement ellipsoid plot (50% probability ellipsoids for non-H atoms) of the asymmetric unit of 1.

3. Supramolecular Features

The structure packs with centrosymmetric π–π dimers, though the distance between least-squares planes formed by non-H atoms of the molecules is beyond the sum of the van der Waals radii at 3.637 Å. Molecules pack in a herringbone pattern with a dihedral angle of 65.2° between the least-squares planes formed by molecules related by the 2₁ screw axis (Fig. 2). The structure has several unique types of intermolecular features. Each molecule participates in centrosymmetric halogen-bonding dimers of Type I (Desiraju & Parthasarathy, 1989 ) with Br⋯Br contacts at 3.582 (1) Å and a C1—Br1⋯Br1 angle of 140.7 (1)° (Fig. 3). Each molecule also engages in two weaker C—H⋯N interactions, one as an sp³-hybridized C5—H5B donor and the other as an acceptor (N1) of this type of interaction (Table 2, Fig. 4). It is noteworthy that the two methylene hydrogen atoms are acidic on account of the electron-withdrawing nature of the cyano group and hence their participation in the formation of C—H⋯N hydrogen bonds is significant. Additionally, atom S1 contributes to two unique intermolecular interactions. S1 acts as acceptor for an interaction with C3—H3 as the donor. These S⋯H interactions are organized in a C₁¹(4) graph-set motif parallel to [101]. An edge-to-face S1⋯π(C1—C2 midpoint) interaction is also present at a distance of 3.391 Å (sum of van der Waals radii = 3.50 Å). These S⋯π close contacts are organized in chains parallel to [010].

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C3—H3⋯S1ⁱ	0.95	2.93	3.844 (5)	162
C5—H5B⋯N1ⁱⁱ	0.99	2.66	3.425 (7)	134
Symmetry codes: (i) $[x+{\script{1\over 2}}, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (ii) $[-x+{\script{3\over 2}}, y-{\script{1\over 2}}, -z+{\script{5\over 2}}]$ .

Figure 2
Packing diagram of 1 showing the herringbone packing pattern.

Figure 3
Intermolecular halogen interaction of 1. Symmetry code: (i) 2 − x, −y, 1 − z.

Figure 4
Intermolecular interactions of 1. Br⋯Br interactions omitted for clarity. π indicates the C1—C2 midpoint. Symmetry codes: (i) $[{3\over 2}]$ − x, − $[{1\over 2}]$ + y, $[{3\over 2}]$ − z; (ii) − $[{1\over 2}]$ + x, $[{1\over 2}]$ − y, − $[{1\over 2}]$ + z; (iii) $[{3\over 2}]$ − x, $[{1\over 2}]$ + y, $[{3\over 2}]$ − z; (iv) $[{3\over 2}]$ − x, − $[{1\over 2}]$ + y, $[{5\over 2}]$ − z; (v) $[{3\over 2}]$ − x, $[{1\over 2}]$ + y, $[{5\over 2}]$ − z; (vi) $[{1\over 2}]$ + x, $[{1\over 2}]$ − y, $[{1\over 2}]$ + z.

4. Hirshfeld surface analysis

Intermolecular interactions were studied further through analysis of the Hirshfeld surface, generated using CrystalExplorer (McKinnon et al. 2007 ; Spackman & Jayatilaka, 2009 ). Fig. 5 shows two orientations of the Hirshfeld surface mapped over d_norm. The red areas of the surface indicate negative d_norm values corresponding to contacts closer than the sum of van der Waals radii and highlight the relevant intermolecular interactions discussed. The relative surface-area contributions from the particular interatomic contacts described for 1 to the total Hirshfeld surfaces are summarized in Table 3. While N⋯H contacts comprise the largest percentage of contacts to the Hirshfeld surface described, the angular and distance components involved in the C—H⋯N hydrogen-bonding interactions do not suggest that these interactions dominate the packing. The Br⋯Br contacts comprise the smallest percentage of interatomic contacts described, however these Br⋯Br atom contacts [3.582 (1) Å] are the shortest of all the contacts described, relative to the van der Waals radii sums (−0.118 Å). The observation that C⋯C contacts comprise only a small percentage of the interatomic contacts is consistent with minor π–π stacking contributions and the observed stacking distance beyond the sum of the van der Waals radii.

Table 3
Percentage contributions of interatomic contacts to the Hirshfeld surface

Contact	%
N⋯H/H⋯N	21.8
S⋯H/H⋯S	10.3
S⋯C/C⋯S	6.9
C⋯C	4.1
Br⋯Br	1.9

Figure 5
Hirshfeld surface of 1 mapped over d_norm, shown in two orientations in the range −0.0639 to 0.93667 a.u. Red areas highlight intermolecular contacts shorter than the sum of the van der Waals radii.

5. Database Survey

A search of the current version of the Cambridge Structural Database (Version 5.39, updated November 2017; Groom et al., 2016 ) yields a number of related structures with a 5-bromothiophene fragment but only two non-salt structures with exclusively one small substituent in the 2-position. The structure of 2-acetyl-5-bromothiophene (ACBTHO; Streurman & Schenk, 1970 ) is planar like 1, but the acetyl group is syn-periplanar relative to the sulfur of thiophene, and Br⋯O=C interactions are present in the absence of Br⋯Br interactions. The structure of a co-crystal of 5-bromothiophene-2-carboxylic acid with 5-fluorouracil (CAWCAP; Mohana et al., 2017 ) is also similar, with no Br⋯Br interactions but the presence of Br⋯O=C interactions. No other structures of any substituted 2-thiopheneacetonitrile have been reported.

The Type I Br⋯Br halogen-interaction pattern of 1 is very similar to three other structures reported with only one bromine donor in the 5-position and no substitution in the 3- or 4-positions of the thiophene group. The structures of 2-bromo-5-[4-(4-nitrophenyl)buta-1,3-dien-1-yl]thiophene (MUJTUH; Kanibolotsky et al., 2009 ), (2E)-1-(5-bromo-2-thienyl)-3-(4-ethylphenyl)prop-2-en-1-one (PUSKUL; Naik et al., 2015 ), and (2RS,4SR)-2-exo-(5-bromo-2-thienyl)-7-chloro-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine (YUCTIA; Blanco et al., 2009 ) have short intermolecular Br⋯Br contacts with distances of 3.4619 (4), 3.4917 (5), and 3.5234 (7) Å, respectively, and centrosymmetric interactions with C—Br⋯Br angles of 145.12 (9), 151.37 (8), and 143.8 (1)°, respectively.

6. Synthesis and Crystallization

The title compound, 2-(5-bromothiophen-2-yl)acetonitrile, was prepared according to the literature procedure (Lu et al., 2014). Additional purification was performed by vacuum distillation (b.p. 334 K @ 0.07 mm Hg), which provided a colorless liquid that crystallized over several days to afford colorless crystals (m.p. 302–305 K) suitable for X-ray diffraction. EI–MS m/z (relative intensity) 202.88 (29.9), 200.89 (29.7), 123.02 (8.6), 122.01 (100.0), 95.03 (11.1).

7. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 4. H atoms were placed in calculated positions and refined in the riding-model approximation with distances of C—H = 0.95 and 0.99 Å for the thiophene and methylene groups, respectively, and with U_iso(H) = 1.2U_eq(C).

Table 4
Experimental details

Crystal data
Chemical formula	C₆H₄BrNS
M_r	202.07
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	173
a, b, c (Å)	9.775 (4), 7.278 (3), 10.698 (4)
β (°)	110.933 (8)
V (Å³)	710.8 (5)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	6.00
Crystal size (mm)	0.51 × 0.44 × 0.22

Data collection
Diffractometer	Rigaku XtaLAB mini
Absorption correction	Multi-scan (REQAB; Rigaku, 1998 )
T_min, T_max	0.141, 0.267
No. of measured, independent and observed [F² > 2.0σ(F²)] reflections	6585, 1444, 1198
R_int	0.048
(sin θ/λ)_max (Å⁻¹)	0.625

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.048, 0.117, 1.07
No. of reflections	1444
No. of parameters	82
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.55, −0.82
Computer programs: CrystalClear-SM Expert (Rigaku, 2011 ), SIR2004 (Burla et al., 2005 ), SHELXL2013 (Sheldrick, 2015 ), Mercury (Macrae et al., 2008 ), publCIF (Westrip, 2010 ) and CrystalStructure (Rigaku, 2014 ).

A single low-angle reflection was rejected from these high-quality data sets due to the arrangement of the instrument with a conservatively sized beam stop and a fixed-position detector. The large number of reflections in the data sets (and the Fourier-transform relationship of intensities to atoms) ensures that no particular bias was thereby introduced.

Supporting information

CCDC reference: 1817195

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S2056989018000968/dx2004sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989018000968/dx2004Isup2.hkl

checkCIF report

Computing details top

Data collection: CrystalClear-SM Expert (Rigaku, 2011); cell refinement: CrystalClear-SM Expert (Rigaku, 2011); data reduction: CrystalClear-SM Expert (Rigaku, 2011); program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2015); molecular graphics: Mercury (Macrae et al., 2008) and publCIF (Westrip, 2010); software used to prepare material for publication: CrystalStructure (Rigaku, 2014).

2-(5-Bromothiophen-2-yl)acetonitrile top

Crystal data top

C₆H₄BrNS	F(000) = 392.00
M_r = 202.07	D_x = 1.888 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71075 Å
a = 9.775 (4) Å	Cell parameters from 5750 reflections
b = 7.278 (3) Å	θ = 3.5–26.5°
c = 10.698 (4) Å	µ = 6.00 mm⁻¹
β = 110.933 (8)°	T = 173 K
V = 710.8 (5) Å³	Prism, colorless
Z = 4	0.51 × 0.44 × 0.22 mm

Data collection top

Rigaku XtaLAB mini diffractometer	1198 reflections with F² > 2.0σ(F²)
Detector resolution: 6.849 pixels mm^-1	R_int = 0.048
ω scans	θ_max = 26.4°, θ_min = 3.5°
Absorption correction: multi-scan (REQAB; Rigaku, 1998)	h = −12→12
T_min = 0.141, T_max = 0.267	k = −9→9
6585 measured reflections	l = −13→13
1444 independent reflections

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.048	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.117	H-atom parameters constrained
S = 1.07	w = 1/[σ²(F_o²) + (0.0495P)²] where P = (F_o² + 2F_c²)/3
1444 reflections	(Δ/σ)_max < 0.001
82 parameters	Δρ_max = 0.55 e Å⁻³
0 restraints	Δρ_min = −0.82 e Å⁻³
Primary atom site location: structure-invariant direct methods

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Refinement was performed using all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F². R-factor (gt) are based on F. The threshold expression of F² > 2.0 sigma(F²) is used only for calculating R-factor (gt).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Br1	0.90954 (6)	0.12818 (8)	0.59072 (5)	0.0348 (2)
S1	0.76060 (13)	0.07396 (16)	0.79952 (11)	0.0242 (3)
N1	0.8679 (6)	0.3162 (8)	1.2745 (5)	0.0610 (16)
C1	0.9070 (5)	0.1545 (6)	0.7644 (4)	0.0218 (10)
C2	1.0043 (5)	0.2468 (6)	0.8663 (4)	0.0258 (11)
H2	1.0914	0.3016	0.8634	0.031*
C3	0.9592 (5)	0.2517 (6)	0.9801 (5)	0.0261 (11)
H3	1.0143	0.3093	1.0624	0.031*
C4	0.8308 (5)	0.1662 (6)	0.9581 (4)	0.0220 (10)
C5	0.7453 (6)	0.1396 (6)	1.0510 (5)	0.0314 (12)
H5A	0.6437	0.1841	1.0063	0.038*
H5B	0.7410	0.0071	1.0701	0.038*
C6	0.8137 (6)	0.2395 (7)	1.1774 (5)	0.0382 (14)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.0342 (4)	0.0494 (4)	0.0253 (3)	−0.0001 (2)	0.0160 (3)	−0.0028 (2)
S1	0.0219 (7)	0.0271 (6)	0.0233 (6)	−0.0037 (5)	0.0077 (5)	−0.0011 (5)
N1	0.079 (5)	0.077 (4)	0.038 (3)	0.001 (3)	0.034 (3)	−0.012 (3)
C1	0.023 (3)	0.025 (2)	0.019 (2)	0.0048 (19)	0.0088 (19)	0.0027 (17)
C2	0.016 (3)	0.029 (3)	0.032 (3)	0.0024 (19)	0.008 (2)	0.0032 (19)
C3	0.026 (3)	0.027 (3)	0.021 (2)	0.001 (2)	0.005 (2)	−0.0052 (18)
C4	0.023 (3)	0.024 (2)	0.021 (2)	0.0026 (19)	0.009 (2)	0.0022 (18)
C5	0.034 (3)	0.036 (3)	0.027 (3)	0.000 (2)	0.013 (2)	0.002 (2)
C6	0.044 (4)	0.049 (4)	0.028 (3)	0.011 (3)	0.021 (3)	0.006 (2)

Geometric parameters (Å, º) top

Br1—C1	1.877 (4)	C3—C4	1.344 (7)
S1—C1	1.708 (5)	C3—H3	0.9500
S1—C4	1.723 (4)	C4—C5	1.523 (7)
N1—C6	1.131 (7)	C5—C6	1.468 (7)
C1—C2	1.343 (6)	C5—H5A	0.9900
C2—C3	1.436 (6)	C5—H5B	0.9900
C2—H2	0.9500

C1—S1—C4	90.7 (2)	C3—C4—C5	129.8 (4)
C2—C1—S1	113.5 (4)	C3—C4—S1	111.8 (3)
C2—C1—Br1	126.8 (4)	C5—C4—S1	118.4 (3)
S1—C1—Br1	119.4 (3)	C6—C5—C4	111.2 (4)
C1—C2—C3	110.9 (4)	C6—C5—H5A	109.4
C1—C2—H2	124.5	C4—C5—H5A	109.4
C3—C2—H2	124.5	C6—C5—H5B	109.4
C4—C3—C2	113.0 (4)	C4—C5—H5B	109.4
C4—C3—H3	123.5	H5A—C5—H5B	108.0
C2—C3—H3	123.5	N1—C6—C5	179.2 (6)

C4—S1—C1—C2	−0.1 (4)	C2—C3—C4—S1	0.8 (5)
C4—S1—C1—Br1	−174.5 (3)	C1—S1—C4—C3	−0.4 (4)
S1—C1—C2—C3	0.6 (5)	C1—S1—C4—C5	−179.6 (4)
Br1—C1—C2—C3	174.5 (3)	C3—C4—C5—C6	5.7 (7)
C1—C2—C3—C4	−0.9 (6)	S1—C4—C5—C6	−175.2 (3)
C2—C3—C4—C5	179.8 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···S1ⁱ	0.95	2.93	3.844 (5)	162
C5—H5B···N1ⁱⁱ	0.99	2.66	3.425 (7)	134

Symmetry codes: (i) x+1/2, −y+1/2, z+1/2; (ii) −x+3/2, y−1/2, −z+5/2.

Percentage contributions of interatomic contacts to the Hirshfeld surface top

Contact	%
N···H/H···N	21.8
S···H/H···S	10.3
S···C/C···S	6.9
C···C	4.1
Br···Br	1.9

Funding information

The authors acknowledge St. Catherine University and NSF–MRI award No. 1125975, MRI Consortium: Acquisition of a Single Crystal X-ray Diffractometer for a Regional PUI Molecular Structure Facility. TMP acknowledges the following: (i) University of Minnesota, Morris (UMM) Faculty Research Enhancement Funds supported by the University of Minnesota Office of the Vice President for Research and the UMM Division of Science and Mathematics for financial assistance, and (ii) The Supercomputing Institute of the University of Minnesota. DEJ acknowledges the Carondelet Scholars program supported by St. Catherine University.

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